Calling the change_multiple_column_values from C# code API

Hi ,
when i am using the change_column_value with C# code with below string :
string query = "{"query" : "mutation { change_column_value(board_id: " + boardId + “, item_id: " + itemId + " , column_id: \"” + columnId + “\", value: \"” + value + “\") { id } }"}”;

it is working but when i am using the change_multiple_column_values with C# code below string :
string query = "{"query" : "mutation { change_multiple_column_values(board_id: " + boardId + “, item_id: " + itemId + " , column_values: "{ \"” + columnId1 + “\" : \"”+ columnValue1 + “\",\"” + columnId2 + “\" : \"” + columnValue2 + “\"}") { id } }"}”;
so its not updating the data and give the error The request was successful but contained no data
so please if i am wrong so please correct me .

Hi @knpashish!

Could you please share the exact error as it’s returned from monday, including any error codes along with it?